1. Field of the Invention
The present invention relates to a signal converting apparatus, and more particularly to a signal conversion apparatus and related conversion method characterized by a fast settling time.
2. Description of the Related Art
Generally speaking, the output of a system having an input/output transfer function will change in relation to changes in an applied input. Within a specified range, the time required for the system output to stabilize following an input change is referred to as “settling time”.
Figure (FIG.) 1 is a general block diagram of a conventional signal converting apparatus. Referring to FIG. 1, signal converting apparatus 100 includes a driving unit 110, an oscillator 130 generating a signal having a periodic sawtooth waveform, a switching transistor 131, and an output unit 133.
Driving unit 110 receives an error signal Verr from an error amplifier (not shown). The error signal Verr swings within a predetermined range, and in response to the error signal Verr driving unit 110 outputs a pulse-width modulated signal to switching transistor 131 when the received error signal Verr remains within its swing range, as defined by the sawtooth waveform provided by oscillator 130 (i.e., between a maximum value and a minimum value for the sawtooth waveform). However, when the error signal Verr exceeds the swing range defined by the sawtooth waveform, driving unit 110 provides a predetermined signal instead of the error signal Verr to switching transistor 131.
Accordingly, switching transistor 131 controls the supply of a predetermined voltage Vo to an inductor L within output unit 133 by being turned ON/OFF in response to the signal provided by driving unit 110. In this manner, driving unit 110 prevents an over-current condition from being applied to switching transistor 131 and the inductor L. However, driving unit 110 exhibits overly long settling times for output voltage Vo applied to output unit 133.